| PI Name | Title |
|---|---|
| Paerels | The Mass and Radius of a Neutron Star: Chandra LETGS Observations of RX J1856.5-3754 |
| Romani | Neutron Star Atmospherics: Towards the Mass and Radius of the Nearest Isolated Neutron Star |
| Walter | The Atomosphere and Interior of the Isolated Neutron Star RX J185635-3754 |
PI: Frederik Paerels
Proposal Title: The Mass and Radius of a Neutron Star:
Chandra LETGS Observations of RX J1856.5-3754
Abstract:
We propose to make a comprehensive analysis of the full Chandra
dataset of observations of the isolated neutron star RX J1856.5-3754. Our
preliminary analysis of the first 50 ks of data indicates the presence of
absorption features in the LETG spectrum; with 500 ks of data we will
characterize these features precisely, search for related features to confirm
atomic identifications, and, potentially, measure both the mass and radius of
this neutron star to ~10 % precision. Such a measurement would have immediate
implications for the equation of state of bulk matter at greater than nuclear
densities -- a regime where no other experimental constraints on -->
-- theory exist or can be expected.
=====================================================================================
PI: Roger Romani
Proposal Title: Neutron Star Atmospherics:
Towards the Mass and Radius of the Nearest Isolated Neutron Star
Abstract:
Identification of neutron star surface spectral features would
strongly impact compact object physics and determine the high density EOS.
RXJ185635-3754 provides the best hope of such measurement, as colors indicate
strong opacity. However, existing data limits line EWs to values well below
those of simple models. After pioneering the basic models, we have recently
modeled rotational effects, surface re-heating and magnetic line shifts. These
will be treated in the proposed work; they can account for the EW decrease, aid
in line identification and are likely crucial to interpretation of the LETG
spectrum. With our sophisticated atmosphere models and codes for
(phase-resolved) spectral fitting, we will extract the best possible M and R
constraints, whether or not lines are detected.
=====================================================================================
PI: Frederick Walter
Proposal Title: The Atmosphere and Interior of the Isolated Neutron Star RX J185635-3754
Abstract:
We request funding to analyze the spectrum of the isolated neutron
star RX J185635-3754. Our analysis of the multiwavelength spectral energy
distribution indicates that the surface composition is heavy elements, and not
Hydrogen. We find a tight contraint on the gravitational redshift, suggesting
that the star is more compact than most realistic equations of state allow. The
short CHANDRA LETG GTO spectrum has marginal S/N for detecting the expected
absorption lines; the deep DDT exposure will permit us to determine the surface
composition, gravitational redshift, and possibly the surface magnetic field
strength. We will use the X-ray spectrum in concert with the full
multi-wavelength spectral energy distribution to assess the surface temperature
structure.
Last modified: 12/02/10
